1. Field of the Invention
This invention relates to components for an insulating glazing unit and to methods of making same and, in particular, to a spacer and spacer frame for an insulating glazing unit and methods of making same.
2. Discussion of the Technical Problems
It is well recognized that insulating glazing units reduce heat transfer between the outside and inside of a home or other structures. A measure of insulating value generally used is the xe2x80x9cU-valuexe2x80x9d. The U-value is the measure of heat in British Thermal Unit (BTU) passing through the unit per hour (Hr) per square foot (sq.ft.) per degree Fahrenheit (xc2x0 F.). As can be appreciated the lower the U-value the better the thermal insulating value of the unit, i.e. higher resistance to heat flow resulting in less heat conducted through the unit. Another measure of insulating value is the xe2x80x9cR-valuexe2x80x9d which is the inverse of the U-value. Still another measure is the resistance (RES) to heat flow which is stated in Hr-xc2x0 F. per BTU per inch of perimeter of the unit. In the past the insulating property, e.g. U-value given for an insulating unit was the U-value measured at the center of the unit. Recently it has been recognized that the U-value of the edge of the unit must be considered separately to determine the overall thermal performance of the unit. For example, units that have a low center U-value and high edge U-value during the winter season exhibit no moisture condensation at the center of the unit, but may have condensation or even a thin line of ice at the edge of the unit near the frame. The condensation or ice at the edge of the unit indicates that there is heat loss through the edge of the unit and/or frame i.e. the edge has a high U-value.
Through the years, the design of and construction materials used to fabricate insulating glazing units, and the frames have improved to provide framed units having low U-values. Several types of insulating glazing units presently available, and or center and edge U-values of selected ones, are taught in U.S. patent application Ser. No. 07/468,039 assigned to PPG Industries, Inc. filed on Jan. 22, 1990, in the names of P. J. Kovacik et al. and entitled METHOD OF AND APPARATUS FOR JOINING EDGES OF GLASS SHEETS, ONE OF WHICH HAS AN ELECTROCONDUCTIVE COATING AND THE ARTICLE MADE THEREBY, and U.S. Pat. Nos. 3,919,023; 4,431,691; 4,807,419; 4,831,799 and 4,873,803. The teachings of the patent application and patents are hereby incorporated by reference.
U.S. patent application Ser. No. 07/578,696 filed even date in the names of Stephen C. Misera and William R. Siskos and entitled INSULATING GLAZING UNIT HAVING A LOW THERMAL CONDUCTING EDGE AND METHOD OF MAKING SAME teaches the design of and methods of making an insulating unit having a low thermal conducting edge. In Section 2 Discussion of Available Insulating Units, the drawbacks and/or limitations of the insulating units of the above identified patent application and patents are discussed. The teachings of U.S. patent application Ser. No. 07/578,696 are hereby incorporated by reference.
As can be appreciated, it would be advantageous to provide a spacer and spacer frame, and method of making same that can be used to fabricate insulating units taught in U.S. patent application Ser. No. 07/578,696 as well as other types of insulating units.
This invention covers a strip for shaping into spacer stock for use in the fabrication of insulating units. The strip includes a metal substrate having a bead of moisture and/or gas pervious adhesive secured to a surface of the substrate. The metal substrate after forming into the spacer stock e.g. U-shaped spacer stock can withstand higher compressive forces than the bead.
The invention also covers a method of making U-shaped spacer stock for use in fabricating a spacer frame for insulating units. The method includes the steps of passing a metal substrate having a bead of moisture and/or gas pervious adhesive positioned on a surface between spaced pairs of roll forming wheels shaped to gradually bend the metal substrate about the bead into spacer stock having a predetermined cross sectional shape, e.g. U-shaped cross section.
Further, the invention covers a spacer frame for an insulating unit, the spacer frame having a groove to define opposed outer sides and having at least one continuous corner, and methods of making same. A method includes the steps of providing a section of spacer stock sufficient to make a frame of a predetermined size. Opposed surfaces of the spacer stock are biased inwardly while the spacer stock is bent about the depressions of the spacer stock to form a continuous corner. The step to form a continuous corner is repeated until the opposite ends are brought together and sealed e.g. by welding.